Disk brake for a bicycle

ABSTRACT

A brake disk rotatable in synchronism with a wheel and arranged adjacent a bicycle frame to which a pair of brake arms constituting a force doubling mechanism substantially operable by a single lever are mounted to be swung at both sides of said brake disk, said brake arms being provided in one end with a pair of brake shoes and in the other end with a link device constituting a force doubling mechanism substantially operable by a toggle joint, and said link device being operable by wire rope means in the manner of securing the most reliable and effective braking contact of said brake shoes upon the brake disk with light manipulation touch.

United States Patent Kine [451 Aug. 1, 1972 [54] DISK BRAKE FOR ABICYCLE [72] Inventor: Masayoshi Kine, clo Shimano 1n dusTth a1 Co.Ltd., No. 77, 3-cho, Oimatsu-clio, Sakai, B9513 g [22] Filed: July 13,1970 21 Appl. No.: 54,363

[30] Foreign Application Priority Data Dec. 23, 1969 Japan ..44/ 122801[52] US. Cl ..l88/24, 188/729 [51] Int. Cl. ..B62l 1/16 [58] Field ofSearch ..188/59, 24, 26, 72.6, 72.9

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 541,983 10/1922France ..l88/24 872,326 2/1942 France ..l88/24 875,535 6/1942 France..l88/24 898,290 7/1944 France 1 88/24 903,429 l/ 1945 France 1 88/2450,593 3/1910 Switzerland l 88/72.9

Primary Examiner-Duane A. Reger Attorney-McGlew and Toren [57] ABSTRACTA brake disk rotatable in synchronism with a wheel and arranged adjacenta bicycle frame to which a pair of brake arms constituting a forcedoubling mechanism substantially operable by a single lever are mountedto be swung at both sides of said brake disk, said brake arms beingprovided in one end with a pair of brake shoes and in the other end witha link device constituting a force doubling mechanism substantiallyoperable by a toggle joint, and said link device being operable by wirerope means in the manner of securing the most reliable and effectivebraking contact of said brake shoes upon the brake disk with lightmanipulation touch.

3 Claim, 9 Drawing Figures P ATEN'Ti-il'lwc" I I972 SHEH 2 OF 5 I I NVENTOR MASAYOSHI KINE BY m a f PATENIEDA E I I97? 4 3.680.663

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Inc 641w fall/V HI I PATENTEDMIB H912 3,680 663 SHEET. 5 BF 5 INVENTOF?HAS/4 YOSHI KIA/E BY v I! (now rue! A TT DISK BRAKE FOR A BICYCLE Thisinvention relates to a disk brake mechanism to be used for a safetybicycle of the most common type. Conventionally speaking, a disk brakemechanism is widely in use especially for an automobile or any othersimilar vehicles, and its mechanical elements are composed of a brakedisks which are rotatable with wheels and of brake shoes which arearranged in opposed relation with each of these disks in the manner thatwhen the brake shoes are pressed against these disks, the rotation ofthe brake disks or the rotation of the wheels is forcibly brought to ahalt. As a means for operating said brake shoes against the wheels ofthe automobile or the like is commonly applied a hydraulic brake shoeoperating means. However, when this type of the means is applied, it isinevitably accompanied with a great disadvantages that the mechanicalconstruction as a whole cannot but be excessively complicated.

Referring to a disk brake mechanism applicable to a bicycle, such a typehas been well known that brake shoes are provided with brake arms, andthe extremities of these brake arms are disposed in such a manner as toconnect with a cam means so that when said cam means is moved, the brakearms are swung in one direction and the rotation of a wheel shaft isstopped by means of the brake shoes. However, said disk brake for abicycle has disadvantages in that it is to be operated through means ofthe cam means, and gives a cycler a sense of very ponderous handoperation, as a consequence, often causing him to fail in accuratelycontrolling the disk brake; on the top of that, said disk brake has anadditional disadvantage in that it requires an excessively complicatedstructure for moving the cam means.

Thus the present invention aims at eliminating the above-mentioneddefects and disadvantages of the conventionally well known disk and atthe same time obtaining such a disk brake that is very simple instructure and controllable by easy manipulation. Accordingly, the mainobject of the invention is to provide a disk brake for a bicycle thatcan be controllably braked by a slight force alone in the exact and safemanner. Another object of the invention is to provide a disk brake for abicycle that the operational mechanism thereof is much simplified andthe brake lever of manipulating said disk brake can be mounted in anyfree portion of a bicycle frame member so as to enable a cycler tomanipulate the brake with great ease and high safety. Further anotherobject of the invention is to provide a disk brake for a bicycle thateven though it has been abrassively worn away until at last to produce achange in its braking effect, it is yet at any time ready for adjustmentsuitable enough to give full play to its normal braking effect.

Further another object of the invention is to provide such a disk brakethat can promptly act the excessively increased braking force upon thebrake lever when it has just operated beyond its predetermined extentthereby making it always possible to secure the exact and quick brakingeffect.

Moreover another object of the invention is to provide such a disk brakethat when it is in braking operation, the brake shoes are moved inparallel to the disk and synchronously brought into contact throughouttheir surface with the brake disk under equal pressure, thereby securinga good braking effect.

Accordingly, the present invention is characterized in that the brakeshoes are integrally operable by combined use of a toggle joint typeforce doubling mechanism and a lever type force doubling mechanism.

While the novel constructions of the invention are as defined in what isclaimed, the detailed description of the invention is as specifiedhereinafter.

Firstly setting forth the accompanying drawings,

FIG. 1 is a side elevation view showing a main bicycle body to which thedisk brake of the present invention is applied,

FIG. 2 is a plan view in which the brake mechanism of the invention isshown in enlarged form and mounted on a bicycle frame member,

FIG. 3 is a side elevation view of the same,

FIG. 4 is a cross-sectional view taken on the line 4- 4 of FIG. 2,

FIG. 5 is a cross-sectional view taken on the line 5- 5 of the same,

FIG. 6 is a diagrammatic view illustrating the operational state of thebrake embodied in accordance with the invention,

FIG. 7 is an illustration of a link mechanism disassembled to individualcomponents,

FIGS. 8 and 9 are both illustrative of further modifications indisclosed embodiments, and in which especially FIG. 8 is a plan viewpartially showing one of the modified embodiments of the invention, andFIG. 9 is a cross-sectional view taken on the line 9-9 of the same.

Setting forth in detail in the second place the disk brake of theinvention with reference to the accompanying drawings, said disk brakecomprizes a brake disk l'mounted on either a rear wheel A or a frontwheel B in the manner of being rotatable therewith, a pair of brake arms2, 3 swingingly mounted to a bicycle frame member C, a pair of brakeshoes 4, 5 secured respectively to said brake arms 2, 3 in opposedrelation with said brake disk 1, and a mechanism 6 for operating saidbrake arms 2, 3.

In the drawing is illustrated the construction that a brake is mountedon the rear wheel A of a bicycle as is best shown in FIG. I. Said brakedisk 1 is secured to a hub E rotatably mounted on a wheel shaft D fixedto said bicycle frame member C in the center of said rear wheel A in themanner that it can rotate together with the hub E. Said brake disk 1 iscomposed for instance of a metallic plate, hard vulcanized india rubber,vulcanized fiber or any other suitable material.

The brake arms 2, 3 are to be pivotally mounted in horizontal relationto one of the bicycle frame members C arranged adjacent said brake diskI, and they are substantially pivoted by means of pivots 22, 23 on thetop surface of a separable clip 21 encircling said bicycle frame memberC and rigidly fixing the same as shown in FIGS. 2 and 3.

The pivoting point where these brake arms 2, 3 are pivoted is positionedcloser toward the brake disk 1 from the center of their lengthwisedirection. The deviation of this pivoting point of the brake arms 2, 3from their center is freely selected up to a reasonable extent, and ifthe distance is made shorter between said pivoting point and the pointwhere the brake arms 2, 3 act upon the brake disk 1, then these brakearms 2, 3 can of course be operated by a cycler with very lightmanipulation touch. However, in this case, the distance must be made asmuch longer within which the brake arms 2, 3 can operate. Thus theselection of said pivotdistance from the otherend of each of the brakearms 2, 3 to the pivotingpoints 22, 23 is. This positional rela-' tionof said brake arms 2, 3 is selectively changeable by moving aforesaidseparable clip 21 along the bicycle frame member C.

- The movement of the separable clip 21 is easily possible by adjustinga bolt 211 for constrictively fixing the same. A pair of the brake shoes4, immovably I heldbyimeans of shoe holders 24, 25 respectively securedto one end of each of the brake arms 2, 3 are disposed symmetrically inopposed relation with each other in the manner 'of contacting with bothfaces of the brake disk 1 and giving the same a predetermined resistingpower thereby to selectively stop the rotational movement of the brakedisk 1.

. 4, 5 in the'direction where they can keep at a distance from the brakedisk 1.

ln' the other end of eachof the brake arms 2, 3 are perforated holes 27,28 through, which the brake arm operational mechanism 6 hereinafterdescribed is to be mounted to the brake arms 2, 3. By operating said.operatingmechanism 6 the brake arms 2, 3 are swung with said pivotingpoints as their center so that the brake shoes 4, 5 are forcibly broughtinto strong contact with the brake disk 1 on the principles of the leverandfulcrum.

Said brake arm operational mechanism 6 is composed of a pantograph-typelink or a parallelogrammic link device 7, the outer wire 8 having oneend thereof connected to said device 7, and also of the inner wireoperatinghandle lever 10 mounted to a handle rod 1 1.

v Said parallelogrammic link device 7 comprises four link elements toform a parallelogram, wherein, as is clearly shown in FIG. 7, the firstlink element 71 is composed of a pair of sheet plates 713 and 714disposed in opposite relation with each other and provided respectivelywith holes 711 and 712 perforated in proximity of both ends of saidfirst link element 71; the second link element 72 is composed of a pairof paralleled sheet plates 723 and 724 disposed in opposite relationwith each other and provided with holes 721 and 722 perforated inproximity of said second link element 72, the third link element 73 andthe fourth link element 74 are likewise respectively composed of asingle sheet plate 733, 744 provided with holes 731 and 732 perforatedin proximity of both ends of each of the third link element 73 and thefourth link element 74.

A pin 75 for connecting one end of each of the first link element 71 tothe second link element 72 has a 4 a lateral hole 751 formed thereinwith a screw wire 8., Said pin 75 is inserted into the overlapped holes711. and 721 of both thefirst link element'71 and second link element72, and held in said lateral holes, 751 by screwing said one end of theholder 81in lateral hole 751 so that the firstlink element 71 and the rsecond link element 72 can be pivotally, linked.

A pair of pins 76, 76 for pivotally linking one'end of the brake arm 2to each end of the first link element 71 and the third link element 73,and likewise for pivotally' linking one end of the brake arm' 3 to eachendof the second link element 72 and the fourth link element'74 areprovided respectively with a head 761 having a sub stantially largerdiameter than that of said holes 722. and 742 through which thesefourlink elements are linked. 7 I

The hole 27 of said brake arm 2-is overlapped with 712, 732 of the linkelements 71, 73, and likewise the I hole 28 of said brake arm 3 isoverlapped with the holes 722, 742 of the link elements 72, 74 wherebysaid pins 76, 76 are respectively inserted into each of the holes 27,28. After that, said pins 76, .76are suspended stationary by said head76 thereof while the opposed end of said head 761 is caulked so as tomount said pins 76, 76 within said holes 27, 28 therebymaking itpossible to mount said parallelogrammic linkdevice 7 to the brake arms2, 3 and pivotally linking one end. of the first link element 71 to oneend of the third link element 73, and one end of the second link element72 to one end of the fourth link element 74 respectively.

A pin 77 for linking one end of the third link'element 73 to one end'ofthe fourth link element 74 is provided at its upper and lower sides withscrew grooves 771, 771 formed in its outer periphery and also providedin its intennediate portion with a flange portion 7720f a fo'rated'ahole 773 for inserting the inner wire 9 therein;

: Said screw grooves 771, 771 are so'formed as to be screwable to nuts774, 775. The third link element '73 and the fourth link element 74 areoverlapped one another in the manner that the holes 731 and 741are madeinto a single hole, into which then, said nut 774 is inserted thereby topivotally connect the third link element 73 to the fourth link element74. After'that, the inner wire 9 is inserted into the hole 773 and thenut 775 is constrictively tightened thereby-to secure one end of saidinner wire 9.

One end of the outer wire 8 is held by means of the holder 81 screwed tothe lateral hole 751 of the pin 75 I as is shown in FIG. 5. Said holder81 comprises a holding element 811 and a screw portion 813 the outerperiphery of which is provided with a screw groove and in the inside ofwhich is provided a hole 812 for inserting the inner wire 9.

As has been mentioned above, said screw portion 813 has a lock nut 814which secures the fonner to the lateral hole 751 of the pin 75 inscrewed relation therewith. The other end of the outer wire 8 is held bymeans of a wire holder 101 of the handle lever 10 pivotally mounted tothe bicycle handle rod 11. One end of the inner wire 9 is secured to thepin 77 while the other end of the same is, passing through the hole 812of the holder 81 into the inside of the outer wire 8, held by means ofaforesaid handle lever 10. Therefore, when this handle lever is operatedby hand, the inner wire 9 is moved in correlation with the outer wire 8,consequently operating the parallelogramrnic link device 7.

Thus the brake shoes 4, 5 are operated through means of the brake arms2, 3 swung about the pivoting point deviated from their center and alsothrough means of the parallelogrammic link device 7 composed of a togglejoint type force doubling mechanism applied to these brake arms 2, 3.

Accordingly, when the inner wire 9 is drawn by operating the handlelever 10, force is brought to the pivoting point of the link elements71, 72 and the pivoting point of the link elements 73, 74 respectively,with the result that said two pivoting points are swung in the directionwhere they are drawn closer whereby the ends of these link elementspivoted on the pins 76, 76 are moved outwardly.

As have been mentioned above, the brake arms 2, 3 connected to each endof these link elements are swung about the pivoting points deviated fromtheir center and consequently one-sided ends of these brake arms 2, 3are forcibly moved outwardly whereas the other sided ends of the sameare moved inwardly to come closer as is best shown in FIG. 6 so that thebrake shoes 4, 5 secured to said other sided ends are forcibly broughtinto contact with the brake disk 1.

According to the present invention, therefore, the swinging movement ofthe brake shoes 4, 5 toward the brake disk 1 to come into contacttherewith is made possible by providing in combination aparallelogrammic link device constituting a toggle joint type forcedoubling mechanism and the brake arms 2, 3 constituting a single lever.Thus even if the force of pulling the inner wire 9 is substantiallysmall, it brings a very strong force to each end of the link elementsconnected to the brake arms 2, 3 since, in case the pivoting points ofthe link elements are applied force, a pair of virtual trianglessupposed with said pivoting points as their vertexes are forciblypressed from the direction of said vertexes and crushed to change theirshapes. Consequently the brake arms 2, 3 are violently swung to produceby far greater force due to the deviation of each pivoting point wherethey are swung, thereby reliably operating the brake shoes 4, 5.

Accordingly, it is understood that merely by applying small force, thedisk brake of the present invention displays a very great braking effectand operates its'braking contact in the most reliable manner.

In addition, the more the above-mentioned crush by pressure advances,the more quickly and more greatly the force given to each end of thelink elements connected to the brake arms will grow in conformity withthe accepted principles of a toggle joint type force doubling mechanismfor which a parallelogrammic link device is definitely employed in thepresent invention. In other words, the force to stretch out the brakearms is to excessively increase according as the pivoting points to bedrawn closer to each other when drawn by the inner wire will come closeto the line along which there are connected the opposed ends of the linkelements connected to the brake arms. Thus at the final stage of brakingoperation, or at need of emergent braking operation, an extremely goodand reliable braking eflect can be secured.

Incidentally, due to the construction that the holder 81 of the outerwire 8 is screwed into the pin inset in one of the pivoting points ofthe parallelogrammic link device 7, and that the nut 775 for fixing theinner wire 9 is mounted on the pin 77 inset in the other pivoting pointof said device 7, it is quite feasible to selectively adjust theposition where the inner wire 9 is to be fixed by means of said nut 775,so that the configuration of said parallelogrammic link device 7 can beas freely as is preferred.

Thus even if the brake shoes 4, 5 have been worn away and deprived oftheir practically reliable braking effect, they can recover the brakingeffect as reliable as before merely by selectively adjusting theposition of said pivoting points. Besides the embodiments referred to inthe foregoing explanation, the disk brake for a bicycle of the presentinvention is practically modifiable as is shown in FIGS. 8 and 9.Namely, what are shown in FIGS. 8 and 8 are the modified embodiments inwhich the brake shoes 4, 5 are not immediately mounted to the brake arms2, 3 but mounted to operating elements 12, 13 pivoted on said brake arms2, 3 so that the brake shoes 4, 5 can move in parallel relation with thebrake disk 1.

The means for moving said brake shoes 4, 5 in parallel to the brake disk1 is composed of a pin 14 extruded from said one operating element 13,and a guide hole 15 perforated in the other operating element 12, aswell as said operating elements 12, 13 themselves.

One end of said pin 14 has a screw 16 and is constrictively screwed to ascrew hole 17 of the operating element 12 whereas the other end of saidpin 14 is inserted in the guide hole 15 in the manner that it can movein the inside of this guide hole 15 along with swinging movements of thebrake arms 2, 3 thereby preventing the operating elements 12, 13 fromswingingly moving and permitting the same to move in parallel.Designated at 18 is a spring means mounted between the brake arm 2 andthe operating element 12. Likewise designated at 19 is another springmeans mounted between the brake arm 3 and the operating element 13.These two spring means 18 and 19 are there to restore the operatingelements 12 and 13 to their respective original position after the brakehas been applied.

Although a preferred embodiment of this invention is illustrated, itwill be realized that various modifications of the structural detailsmay be made without departing from the mode of operation and the essenceof the invention. Therefore, except insofar as they are claimed in theappended claims, structural details may be varied widely withoutmodifying the mode of operation. Ac cordingly, the appended claims andnot the aforesaid detailed description are determinative of the scope ofthe invention.

Having thus described our invention, what is claimed 1s:

1. A disk brake for a bicycle comprising a brake disk fixedly mounted toa wheel of said bicycle and rotated therewith, said disk comprising apair of opposed, parallel frictional engagement surfaces,

a pair of brake arms pivotally mounted to a frame of said bicycle,

actuating means engaging each of said brake amis at one end thereof tosimultaneously rotate said arrm in an opposed manner about theirrespective pivotal mountings,

a pair of brake shoe elements including brake shoe surfaces forfrictionally engaging said brake disk surfaces, each of said brake shoeelements being pivotally mounted upon one of said brake arms at an endthereof opposite said actuating means,

and guide means engaging each of said brake shoe [0 elements andextending directly therebetween for insuring that said brake shoeelements move with said brake shoe surfaces maintained parallel to 8said brake disk engagement surfaceswhensaidbrakearmsareactuatedtoengagesaid disk brake.

2.Adiskbrakeaccordingtoclaiml,whereinsaid

1. A disk brake for a bicycle comprising a brake disk fixedly mounted toa wheel of said bicycle and rotated therewith, said disk comprising apair of opposed, parallel frictional engagement surfaces, a pair ofbrake arms pivotally mounted to a frame of said bicycle, actuating meansengaging each of said brake arms at one end thereof to simultaneouslyrotate said arms in an opposed manner about their respective pivotalmountings, a pair of brake shoe elements including brake shoe surfacesfor frictionally engaging said brake disk surfaces, each of said brakeshoe elements being pivotally mounted upon one of said brake arms at anend thereof opposite said actuating means, and guide means engaging eachof said brake shoe elements and extending directly therebetween forinsuring that said brake shoe elements move with said brake shoesurfaces maintained parallel to said brake disk frictional engagementsurfaces when said brake arms are actuated to engage said disk brake. 2.A disk brake according to claim 1, wherein said guide means comprise apin mounted to extend between said brake shoe elements, with at leastone of said brake shoe elements being movable relative to said pin.
 3. Adisk brake according to claim 2, wherein said pin is fixed to one ofsaid brake shoe elements and movably mounted relative to the other.